Surgically induced weight loss, including reduction in waist circumference, is associated with improved pulmonary function in obese patients.

BACKGROUND: Obesity is associated with impaired pulmonary function. We evaluated the effect of bariatric surgery on pulmonary function among obese patients and identified potential anthropometric factors of obesity corresponding to the reversal of impaired pulmonary function.
METHODS: Pulmonary function and anthropometric factors were studied in 94 obese patients aged 18-65 years with a body mass index >32 kg/m(2). Pulmonary function tests were performed preoperatively and 3 months after bariatric surgery. The measurements included forced vital capacity (FVC), forced expiratory volume in the first second (FEV(1)), total lung capacity, expiratory reserve volume, residual volume, and diffusing capacity of the lung for carbon monoxide. The anthropometric factors included the body weight, body mass index, waist circumference (WC), hip circumference, waist/height ratio, and waist/hip ratio. The changes in anthropometric parameters were analyzed in relation to pulmonary function test results. Multiple linear regression models were applied to identify the factors that influenced pulmonary function after bariatric surgery.
RESULTS: When measured 3 months after surgery, all anthropometric parameters for the 94 patients studied had significantly decreased, and the pulmonary function test parameters had significantly improved. Of the anthropometric parameters, the reduction in body weight, WC, and waist/height ratio correlated significantly with increases in the FEV(1) and FVC. In the multiple linear regression analysis, only the reduction in WC correlated significantly with the reductions in the FEV(1) and FVC.
CONCLUSION: After bariatric surgery, all anthropometric parameters of obesity decreased significantly and the pulmonary function improved. This improvement correlated best with the reduction in the WC and perhaps a decreased intra-abdominal pressure.